<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>类选择器</title>
    <style>
      /*类选择器：*/
      .box {
        width: 200px;
        height: 200px;
        background-color: pink;
      }
      /* 后代选择器*/
      div span {
        color: red;
      }
    </style>
  </head>
  <body>
    <div class="box1">我是一个盒子</div>
    <div class="box2">我是一个盒子</div>
    <div class="box3">我是一个盒子</div>
    <span>span</span>
    <div><span>divspan</span></div>
  </body>
</html>
